You can channel the curse in your blood to hamper foes that turn their backs on you.

Prerequisite: Wis 13, Improved Unarmed Strike, Knowledge (nature) 3 ranks.

Benefit: While using this style, whenever you deal at least 10 points of damage to a foe with an attack of opportunity, that foe's base speed decreases by 5 feet for 1 round. The foe's base speed decreases by an additional 5 feet for every 5 points of damage your attack deals beyond 10. If this penalty meets or exceeds the remaining number of feet your foe can move during its turn, you may attempt a combat maneuver check to trip your foe as an free action.